A method and an apparatus for acquiring data of dynamic physical processes via a radio link are known from German patent application No. DE 198 07 004 A1. This document also relates to the special problems of the measurement of the strain of a tire element during the contact with the road while the corresponding vehicle is moving. To separate the sensor wave from the exciting wave, a time domain division between the exciting wave and the sensor wave is used. The remote transponder unit, also referred to as a radio sensor, includes a sensor, a transponder antenna, and an energy storing means which stores energy out of the exciting wave until the exciting wave and all environmental echoes are faded away. Then the sensor wave is generated by using the stored energy. The sensor wave encodes the information of the measurement values to be monitored. For energy storing a well known surface acoustic wave device is used which gives back one or several time delayed echoes of the signal which is applied to it. Using these delayed signals, the time domain division between the exciting wave and the sensor wave is implemented. One of the time delayed signals is controlled by a sensor impedance which is sensitive to the measurement value. The instantaneous reflection coefficient of the transponder antenna is not changed by the sensor but the amplitude and phase of one or more of the delayed re-emitted signals is changed. To assure the time domain division the exciting wave must be a pulsed one with a time length less than the storage time, or a so called FMCW-signal (frequency modulated continuous wave) which changes its frequency as a function of time so that the sensor wave differs in frequency from the actual exciting wave. A continuous wave (CW) signal containing one single frequency could not be used because this would destroy the time domain division. To uphold the time domain division between the exciting wave and the sensor wave a very fast sampling has to be performed in the receiver unit, which may be much faster than the sampling necessary to resolve the dynamics of the measurement values.